Process of preparing lead sulfate.



' thereof.

ALEXANDER S. RAMAGE, BUFEALG, NEW YORK, ASSIGNOR T0 INTERNATIONAL- COLOR & CHEMICAL COMPANY, INCORPORATED, OF DETROIT, lVIICHIGAN, A

PORATION 0E NEW YORK.

PROCESS OF IPRIEZIPARIIQC-r LEAD SULFATE.

nieaais. Iiro brewing.

and State of New York, have invented oer-- tain new and useful Improvements in Processes of Preparing Lead Sulfate, of which the following is a specification.

The object of this invention is to provide a simple and economical process of preparing pure sulfate of lead from sulfid ores An illustrative example" in accordance With the invention is as follows :.The suliid ore of lead, usually galena, is charged in the form of powder into a roasting furnace which has been previously heated to dull redness, and is roasted for approximately one hour during which time the admission of air is restricted as far as possible. third of the sulfur is driven 'ofi without materially 'fluxing or' fusing the ore, the

-. temperature rising in the meantime to bright redness. After about one hour, air

isadmitted to the charge, and the latter is stirred, preferably by mechanical devices,

for about another hour, at the end of which period the charge is drawn.

The roasted charge prepared as above is found to consist of a mixture of lead oxid, lead sulfate, and lead sulfid. in approximately equal proportions. This mixture is treated with concentrated nitric acid sufficient proportion to convert the lead oxid to lead nitrate and the lead sulfid to lead sulfate. The nitrous fumes arising from this treatment are permitted to min- 'gle n a tower with the suliiurous gases from again liberated in condition for immediate Under these conditions, about one- Specification of Letters ZEatent. a, Pat gntefl e; 191 Application filed April 18, 1915. Serial No. 21,873.

use, in a repetition of the process. The lead sulfate thus prepared is Washed free'from nitric acid, and is ready for utilization in any desired manner, preferably for conver .sion into basic chromate of lead under the conditions and in the manner described in my copending application, Serial N 0. 21,872, filed April 16,- 1915 In case the sulfid ores contain material percentages of silver, this metal accumu lates in the nitric acid solution in the course of several repetitions of the process; and thi nitric liquor is periodically treated for the recovery of silver, as for example bythe Claudt or other suitable process.

Ielaim:. -V

1. The process of preparingleadsulfate from sulfid ores of, lead, which consists in roasting the ore and thereby producing a mixture containing oXid, sulfate and sulfid of lead; treating the said mixture with nitric acid and combining the evolved nitrous fumes in presence of oxygen with the sulfurous gases from the roasting opera tion; and utilizing the resulting acid products to complete. the conversion of the mix- };urg derived from the ore into sulfate of from sulfid. ores of lead, whichconsists in roasting the ore with restricted access of air during the preliminary roasting stages and furous gases from the roasting operation thereby forming sulfuric and nitro-sulfuric acids; and returnlnglthe ac1d products thus formed to the roasted ore, Wherebythe conversion'of the roasted mixture nto sulfate is completed and thenitric acid is evolved and recovered in available formfor arepetition of the process.

In testimony whereof I 'aflix my signature.

ALEXANDER S. RAMAGE.

2. Theprocess' of preparing lead sulfate Copies 0! this patent may be obtained for 'fiye cents each, by addressing the Commissioner of Patents, i

' Washington, D. Q. I 

